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arXiv · 2510.02606

A Mid-Infrared Spectroscopic Study of Young Stellar Objects in the SMC Region NGC 346: JWST Detects Dust, Accretion, Ices and Outflows

Nolan Habel·Omnarayani Nayak·Patrick J. Kavanagh·Olivia C. Jones·Margaret Meixner·Guido De Marchi·Laura Lenkic·Alec S. Hirschauer·Katia Biazzo·Jeroen Jaspers·Conor Nally·Massimo Robberto·Ciaran Rogers·Elena Sabbi·Beth A. Sargent·Peter Zeidler
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Abstract

We present mid-infrared spectroscopic observations of intermediate- to high-mass young stellar objects (YSOs) in the low-metallicity star-forming region NGC 346 located within the Small Magellanic Cloud (SMC). We conduct these integral-field-unit observations with the Mid-Infrared Instrument Medium Resolution Spectroscopy instrument on board JWST. The brightest and most active star-forming region in the SMC, NGC 346 has a metallicity of $\sim$1/5 $Z_{\odot}$, analogous to the era when star formation in the early Universe ($z$$\simeq$2) peaked. We discuss the emission and absorption features present in the spectral energy distributions (SEDs) of five YSOs with coverage from 4.9-27.9$\mu$m and three other sources with partial spectral coverage. Via SED model-fitting, we estimate their parameters, finding masses ranging from 2.9-18.0 M$_{\odot}$. These targets show dusty silicates, polycyclic aromatic hydrocarbons and ices of CO$_2$, CO, H$_2$O and CH$_3$OH in their protostellar envelopes. We measure emission from H$_2$ and atomic fine-structure lines, suggesting the presence of protostellar jets and outflows. We detect H I lines indicating ongoing accretion and estimate accretion rates for each source which range from 2.50x10$^{-6}$-2.23x10$^{-4}$ M$_{\odot}$yr$^{-1}$ based on H I (7-6) line emission. We present evidence for a $\sim$30,000AU protostellar jet traced by fine-structure, H I and H$_2$ emission about the YSO Y535, the first detection of a resolved protostellar outflow in the SMC, and the most distant yet detected.

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Nolan Habel, Omnarayani Nayak, Patrick J. Kavanagh, Olivia C. Jones, Margaret Meixner, Guido De Marchi, Laura Lenkic, Alec S. Hirschauer, Katia Biazzo, Jeroen Jaspers, Conor Nally, Massimo Robberto, Ciaran Rogers, Elena Sabbi, Beth A. Sargent, Peter Zeidler. 2025-10-02. A Mid-Infrared Spectroscopic Study of Young Stellar Objects in the SMC Region NGC 346: JWST Detects Dust, Accretion, Ices and Outflows. https://doi.org/10.3847/1538-4357/ae0c14

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